2 (4,4&#39;bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid



Patented Jan. 4, 1949 *2(4:,{1'BIS DIMETHYLANIINOBENZOHYDRYL) DIZMEIHYLAMINOBENZOIC ACID Clyde S..Adams, Yellow Springs, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a. corporation of Maryland No Drawing. Application June 16, 1945, Serial No. 599,968

1 Claim. (Cl. 260-, 39l) 1 2 This invention relates to the new compound with m-di-methylaminobenzoic acid, having. the 2(4,4'bis dimethylaminobenzohydryD5 dimethstructure ylaminobenzoic acid, having the structure 002E (CHQZN mom 5 \C WHa):

\ Michlers Hydrol may be obtained commerm cially, as it is an important intermediate in the dyestufi industry, but msdimethylaminobenzoie acid is not obtainable even for laboratory use, Mam): so a method of its preparation will be given.

, V a The novel compound a a melting point of Prep ratzon of m dzmethylammobenzoic aczd approximately 199-200 degrees centigrade and crystallizes from hot benzene in gray crystals.

The compound is valuable as an intermediate oxidizable substance in the making of compounds color-responsive to weak acids and to adsorbed 002E polar solids. Specifically, it may be oxidized into i Crystal Violet Lactone, having the formula 3,3

bisfll dimethylaminophenyDB dim'ethylamino phthalide, having the structure The 'm-dimethylaminobenzoic acid may be made by the methylization of m-aminobenzoic acid, having the structure 05 using methyl iodide the presence of an aque- (CHmN mom): ous solution of potassium hydroxide. The m-aminobenzoic acid is obtainable commercially, but

at present only in small amounts. It is, however,

, a well-known compound. The first step in the 0 preparation of m-dimethylaminobenzoic acid is to produce its betain. Seventy grams of m-aminobenzoic acid is dissolved in 700 milliliters of 50% methyl alcohol, using a two-liter flask fitted with a cork. The resulting mixture may be warmed to eflect complete solution. To

Mom), the solution, when cooled, is added 225 grams of methyl iodide, followedby the addition of 105 which is normally colorless but which assumes grams of 5 potassium hydroxide, which is the a blue color in the preSenCE Of Weak acids or approximate strength of rdinary comma m when adsorbed on polar solid substances such as cial product, in three separate Charges f 5 clay. lattertoxidation is ShOVVn in my grams each each 35 gra m charge being previcO-pending application for United States Letters ously dissolved in 100 cc. (ii-50% methyl alcohol. Patent Serial No. 599,967, filed June 16, 1945, The fi t charge is intrgduced into, t flask issued as States MtteI'SPaf/ent NO. is stoppered and to Stand at room temperature until a test shows that the The novel compound may be Prepared by solution is acid. The second and third charges densing Michlers Hydrol, having the Structure are added successively, the timing of the third 5: charge, as in the case of the second charge,

awaiting the event of the acid condition of the OZO solution. The solution is allowed to stand until H the disappearance of the methyl iodide which saponify the esterf forms a separate layer at the bottom of the flask. This period of methylation usually requires from three to five days.

The contents of the flask are now subjected to distillation until most of the methyl alcohol has been distilled over. The remaining aqueous solution is cooled, and 75 milliliters of concentrated hydrochloric acid (37% gas content by weight) is added. On standing and cooling, white crystals of the hydrated hydriodic acid salt of mtrimethylbenzbetain separate out. These crystals are filtered off and air dried.

The betain, which has the structure is next converted to the methyl ester of mdimethylaminobenzoic acid in the following manner. Enough of the betain prepared in accordance with the preceding step to make 100 grams is placed in a wide-mouthed Erlenmeyer flask immersed in an oil bath. The temperature is gradually raised to a point at which the betain begins to melt and decompose, giving off gaseous hydrogen iodide and Water vapor. The temperature slowly climbs to a point at which the decomposition is completed. ,The decomposition should be carried on slowly and carefully to prevent loss of product by entrainment. A light oil, which is essentially the free betain, remains in the flask. The temperature of the oil is then raised to 235 degrees centigrade for approximately fifteen minutes, during which the transition of the betain to the corresponding ester takes place. The ester, having the formula N (CH3) 2 tion made of 100 milliliters of concentrated hydrochloric acid and. l00'milliliters of water. The resulting solution is boiled for five minutes to The hot acid solution of m-dimethylaminobenzoic acid should be treated with activated charcoal and boiled for a few minuteslonger to decolorize it. The resulting mixture is filtered hot. The residual activated charcoal is Washed with a small quantity of hot Water While still on the filter, and the washings'are added to the main filtrate. Y

Next, m-dimethylaminobenzoic acid is isolated from the resulting acid solution. The acid solution of m-dimethylaminobenzoic acid is cooled and partially neutralized with a cold saturated solution of sodium hydroxide. Final neutralization is accomplished by adding sodium carbonate,

solution as long as the precipitate, which first forms, redissolves on stirring. The resulting solution is then treated with a saturated solution of sodium acetate prepared by dissolving 60 grams of hydrated sodium acetate in 50 milliliters of 1 4 water. The resulting mixture is allowed to cool, and the resulting crystals of m-dimethylaminobenzoic acid are filtered off, washed with a small quantity of cold water, and air dried. This crude air-dried product may be further purified by recrystallizing it from its solution in hot benzene.

Condensation of Michlers Hydrol with mdimethylaminobenzoic acid As an example, 18 grams of m-dimethylaminobenzoic acid crystals is mixed and powdered with 27 grams of Michlers Hydrol. The resulting intimate mixture is then added very slowly to 212 grams of sulphuric acid which has been previously cooled to zero degrees centigrade by an ice bath. The sulphuric acid is mechanically stirred during the addition of the mixture. After addition of the mixture, the resulting solution is allowed to stand at room temperature for several hours. The brown acid solution is then poured slowly onto 1,000 grams of ice. The resulting dilute acid solution is then partially neutralized, while being stirred, with a strong sodium hydroxide solution, followed by more precise neutralization accomplished by addingsodium carbonate solution as long as the precipitate, which first forms, redissolves on stirring. Two hundred rams of solid hydrated sodium acetate is then added, the solution being constantly stirred. I The resulting mixture is" permitted to stand several hours in a cool place. The cooled mixture is filtered to recover the solid condensation products, which are washed on the filter with water and thereafter redissolved in a minimum quantity of dilute hydrochloric acid.

The resulting dilute hydrochloric acid solution of the condensation products is neutralized with a sodium hydroxide solution, excess being added to make the solution definitely alkaline. The alkaline solution should be boiled for a few minutes, cooled, and filtered. The alkaline filtrate, containing the sodium saltof 2(4,4'bis dimethylaminobenzohydryl) 5-dimethylaminobenzoic acid, is acidified With acetic acid, care being taken not to add much excess acetic acidafter the solution becomes acid. The free novel compoundnamely, 2 (4,4"bis dimethylaminobenzohydryl) 5-dimethylaminobenzoic' acidcrystal1izes out from the acid solution on cooling and standing.

crystals of 2(4,4bis dimethylaminophenyl)l-dimethylaminobenzoic acid, having a melting point 7 are filtered ofl,

ofv 199-200 degrees centigrade Washed with petroleum ether, and air dried.

mama

What is claimed is: The compound 2(4,4'bis dimethylaminobenzohydryl)S-dimethylaminobenzoic acid, having the structure HshN N(OH;)|

N(OHI)S CLYDE S. ADAMS.

REFERENCES CITED The foljlowing references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 2,130,480 Austin Sept. 20, 1938 OTHER REFERENCES Fischer, Annalen der Chemie, vol. 206, p. 101 (1880).

Haller et a1., Bull. Soc. Chimique de Paris, (3); vol. '25, D. 317 (1901).

Cain et aL, "Synthetic Dyestuffs (1920), pages 1 97 to 98.

Patent No. 2,458,328.

It is hereby numbered pate Column 4,

same may conf Signed and Certificate of Correction certified that err nt requiring correc line 72, for 1di- 0rd sealed this 24 CLYDE S. ADAMS or appears in t1 sh of the case in the th day of May, A

January 4, 1949.

the printed specification of the above on as follows: read 5d'i;

ould be read Wi th this correction therein that the Patent Office. D. 1949.

THOMAS F. MURPHY,

Assistant Oommissioner of Patents. 

